Effect of Additives on the Preparation of Magnesium Oxide with Magnesium Chloride Hexahydrate and Its Hydration Products
In order to solve the problem of large-scale utilization of magnesium resources in salt lake,magnesium sulfate,sodium chloride and ammonia were added from salt lake as raw materials.The effects of different additives and dosages on the preparation of magnesia were investigated.Magnesia hydroxide with different morphology was obtained by hydration reaction.Magnesium oxide and its hydration products were characterized by XRD,SEM and laser particle size analysis.The results showed that the introduction of SO2-4 reduced the pH of magnesium chloride hexahydrate solution,which was not conducive to the growth of magnesium oxide,and fused into large particle morphology.Compared with SO2-4,Na+has stronger damage degree to MgO preparation from magnesium chloride hexahydrate.Na+increased the grain size of the product magnesium oxide,the characteristic particle size reached D50=28.69 μm,and the degree of distortion became worse.There were still incomplete hy-drated MgO after hydration of the prepared MgO,the ratio of diffraction peak I001/I101 was 0.723,and the growth surface of(101)was more exposed,resulting in the thickening of hexagonal lamellae and the products sticking to each other and lamellar accumulation.When the molar ratio of ammonia to magnesium chloride hexahydrate is 0.2,magnesium oxide with flake mor-phology can be prepared,and the characteristic particle size is only D50=1.78 μm.In the application of MgO hydration,all the products are converted to Mg(OH)2,the ratio of I001/I101 is 0.777,the crystal is complete,and the flower cluster is interspersed with hexagonal pieces,which provides a potential application prospect in adsorption purification and other fields.
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